Nearly every neuropsychiatric disorder (e.g., depression & schizophrenia, attention deficit disorder, obsessive compulsive disorder and bipolar disorder) shows deficits in attention control: the ability to attend to behaviorally relevat sensory stimuli and ignore irrelevant stimuli. Attentional control is, of course, a central factor n the attention deficit disorders and is thought to play a significant role in addictive behaviors. These deficits can occur because of impaired suppression of distractions or because of fluctuations in sustaining of attention, when the mind wanders. We propose to develop measures that will allows us to distinguish between these deficits at the neural level, describe their interactions and facilitate tracking of attention performance that is imperative for accurate diagnosis and monitoring of treatment efficacy. To achieve this we will combine the complementary methods of electroencephalography (EEG) (especially relevant to short term processes and spectral specificity) and functional MRI (relevant to slow evolutions in sustained attention and providing spatial specificity not readily observed with EEG) to measure fast and slow changes in attention. These measures will ultimately allow us to explain when and why internal state and distractibility impair behavior. PUBLIC HEALTH RELEVANCE: This project will improve our understanding of the interactions between brain mechanisms that allow us to ignore distractions and brain mechanisms that allow us to sustain attention for extended time periods - both compromised in nearly every neuropsychiatric disorder. We will simultaneously measure brief electrical changes in the brain, occurring on the order of milliseconds, and slower fluctuations in brain metabolism, occurring on the order of seconds and minutes, in order to answer these questions.